1. Field of the Invention
The present invention relates to a display push switch which is adapted to be mounted on a display device and which permits an operator to observe an image displayed on the display device through a key top member.
2. Description of the Prior Art
Various types of display switches have heretofore been proposed. One known type of the prior art display switch includes a key top member positioned about an image plane of a display device which displays an image corresponding to the key top member. Another known type of the prior art display switch includes a touch panel made of transparent material such as plastics and glass and positioned above an image plane of a display device. Still another known type of the prior art display switch includes a key top member which constitutes an image plane by itself.
The first-mentioned display switch involves the problem that an additional space for the key top member is required about the image plane, so that the display switch must be larger in size. Additionally, if the key top member plural in number, an operator cannot readily realize the relationship between the image displayed on the image plane and its corresponding key top member. Further, it is liable to cause mistaking of the key top member to be selected. With the second-mentioned display switch, the touch panel is fixed in position and therefore, click feeling or a stroke feeling cannot be obtained. With the third mentioned display switch, since one display device such as an LCD (liquid crystal display) is required for each key top member, a controller (or a driver circuit) and a backup light device is required for each display switch. This may lead to increased manufacturing costs when a plural number of the display switches each having a key top member are to be provided. The manufacturing costs may be further increased if a graphic image or a colored image is to be displayed.